1. Field of the Invention
The present invention relates to a composite writing utensil in which a plurality of writing members, at least one of which is a propelling pencil writing member, are housed within a shaft barrel, capable of selectively projecting the tip of a desired one of the writing members from the tip of a front shaft so as to be maintained in a writing position, and more particularly to a composite writing utensil improved in refilling the propelling pencil writing member with lead.
2. Description of the Related Art
In the composite writing utensil, when refilling the propelling pencil writing member with a lead, it has been conventionally proposed to render a lead capable of being inserted from the rear end of the shaft barrel, as in the case with an ordinary, single writing utensil which is not a composite writing utensil, for facilitating a refilling operation of a lead (see, for example, Japanese Patent Laid-Open No. 11-314491 or U.S. Pat. No. 6,315,477).
In, for example, the composite writing utensil disclosed in Japanese Patent Laid-Open No. 11-314491, a sliding piece fixed to the rear end of a lead case pipe of the propelling pencil writing member is provided with a cam oblique surface on a rear side thereof for contacting a cam inclined surface of a cylinder cam and is provided with a lead penetrating hole for communicating with the lead case pipe of the propelling pencil writing member. The cylinder cam is also provided with another substantially similar cam inclined surface inside of the cam inclined surface to which the sliding piece always opposes with a minimum clearance. Also the cylinder cam is provided with a lead penetrating hole for aligning with the lead penetrating hole of the sliding piece when the sliding piece is in the most retracted position. A lead fastening device for allowing the lead penetrating hole of the cylinder cam to an opened state or a blockaded state is mounted onto the cylinder cam. When refilling with lead, the propelling pencil writing member is placed at the most retracted position and the lead fastening device is drawn backward so as to set the lead penetrating hole of the cylinder cam to the opened state, a lead is inserted through the lead penetrating hole in the opened state.
In the composite writing utensil disclosed in U.S. Pat. No. 6,315,477, a tip of a cylindrical tube is telescopically disposed into a rear end of a lead case pipe of a propelling pencil writing member, and the rear end of the cylindrical tube extends as far as near the rear end of the housing. Thus, when refilling with lead, a cap on the rear part of the housing is removed to insert lead through the rear end of the cylindrical tube.
In the writing member described in the former publication, however, a problem is that lead cannot be refilled unless the propelling pencil writing member is placed at the most retracted position in order that the lead penetrating hole of the sliding piece coincides with that of the cylinder cam. In contrast to this, in the writing member described in the latter publication, it is possible to refill with lead regardless of the position of the propelling pencil writing member.
In order to smoothly move a plurality of writing members to and fro within the shaft barrel, a guide shaft which rotates together with the front shaft for guiding the sliding piece (or slider) in the back-and-forth direction is desirably provided within the rear shaft. In the case that the guide shaft is provided, structure and space for mounting the guide shaft within the rear end portion of the rear shaft are required. A problem is that it becomes difficult to set a lead penetrating path leading to the propelling pencil writing member. In the structure described in the above patent publications, since no guide shaft has been provided in the structure, the space formed in the rear end part of the rear shaft can be utilized as a lead penetrating path comparatively freely. However, there are no disclosure concerning structure in which the guide shaft can be securely mounted to the rear shaft and lead can be refilled at whichever position i.e. either one of in the most retracted position, the most advanced position and any intermediate position between them, the propelling pencil writing member may be located in the prior publications.